Magnetic core memory system for control of moveable members



P. M. CASTLE Feb. 24, 1970 MAGNETIC CORE MEMORY SYSTEM FOR CONTROL OF MOVE ABLE MEMBERS Filed Jan. 23, 1967 2 Sheets-Sheet 1 PATRICK M. CASTLE INVENTOR BUCKHORM'BLORE KLAROU/ST 8 SPARKMAAZ ATTORNEYS Feb. 24, 1970 P. M. CASTLE 3,497,714

MAGNETIC CORE MEMORY SYSTEM FOR CONTROL OF MOVEABLE MEMBERS Filed Jan. 25, 1967 2 Sheets-Sheet 2 FIG. 2

..|o 6(2 i A 94 F 2 so 58 :78 i I :74 t I76 I32 I20 r g F I I PATRICK M. CASTLE M/VE/VTOR BUCKHORN, BLORE, KLAROU/ST 8 SPARK/MAN ATTORNEYS United States Patent Ofifice Patented Feb. 24, 1970 3,497,714 MAGNETIC CORE MEMORY SYSTEM FOR CONTROL OF MOVEABLE MEMBERS Patrick M. Castle, Hillsboro, Oreg., assignor to Rodgers Organ (10., Hillsboro, Greg, a corporation of Oregon Filed Jan. 23, 1967. Ser. No. 610,849 Int. Cl. HOlh 9/00 US. Cl. 307-112 17 Claims ABSTRACT OF THE DISCLOSURE A capture system for stop tablets in an electronic organ or pipe organ. The positions of a plurality of stop tablets are stored ina magnetic memory and may be retrieved at will for physically positioning the stop tablets. The stop tablets provide both input and output means for the magnetic memory as well as temporary storage means to prevent destruction of stored information during readout.

BACKGROUND OF THE INVENTION This invention relates to a memory switching system and particularly to such a system wherein a magnetic memory controls the physical position of movable switching devices.

In my application Ser. No. 345,159, filed Feb. 17, 1964, and entitled Memory Switching Circuit, now Patent 3,307,- 050, an apparatus is described and claimed for storing the positions of a plurality of mechanical switches Regardless of the position to which the mechanical switches are manually moved, the switches can be caused to return automatically to their preset stored positions. This apparatus employs magnetic switching devices, e.g. reed switches, for storage elements and is especially useful for Controlling mechanical switching devices in a musical instrument, e.g. the stop tablets or draw knobs in an electronic organ or pipe organ. Before playing the organ, the musician presets various selected combinations of stop tablets and may capture or store these combinations for future reference. While playing the organ, the musician need only close a selected piston associated with a stored combination of stop tablets in order to physically reproduce the preset combination on the stop tablets. The afore mentioned memory switching apparatus has many advantages over conventional combination capture systems in that it is reliable, quiet and less expensive than prior structures. This system also has the advantage of reduced space requirements as compared with prior mechanical systems. Nevertheless, if a considerable number of combination settings are to be stored for furture selec tion, the memory system employing reed switches or the like can be space consuming and somewhat costly.

SUMMARY OF THE INVENTION In accordance with the present invention, a plurality of mechanical switches, e.g., stop tablets or draw knobs on an organ, are interconnected with an array of magnetic core elements for storing at separate locations in the array a plurality of separate combinations of such mechanical switches. The mechanical switches, Which are adapted to be manually set to at least two selectable positions, are also provided with electrical actuating means and electrical position detecting means. The position detecting means intercouple the switches with the magnetic core memory array such that the mechanical switches comprise the input means for the memory array used for entering information therein. The electrical actuating means are also intercoupled with the memory array, whereby the switches additionally act as output means for the memory array. This system is less costly than one employing magnetic reed switches or the like and a considerable number of combination settings may be stored in the magnetic core memory array without a substantial increase in cost.

The apparatus according to the present invention has no moving parts except for the mechanical switches themselves, and the apparatus is uncomplex since an advantageous cooperation is secured between the mechanical switches and the magnetic core array. When a combination setting stored in the array is to be read out, it is read out in the form of the physical position of the mechanical switches. The read out of the magnetic memory is destructive but the information formerly stored at a memory location is now stored in the form of the mechanical positions of the switches. The same information is then immediately re-read into the array since the mechanical switches additionally comprise input means for the memory. The mechanical switches perform a total of four functions: their predetermined function with respect to the organ, as input means for the memory array, as output means for the memory array, and as temporary storage means for the memory array.

According to an additional feature of the present invention, the mechanical switch members may be physically operated substantially directly from signals derived from the magnetic core memory. Each output impulse sensed from the magnetic core memory provides an input applied to the controlling element of a silicon controlled rectifier. The output of the silicon controlled rectifier operates electrical actuating means of a switching member.

An object of the invention is accordingly to provide an improved memory switching system for storing a relatively large number of physical positions of physically movable members, which system is reliable, economical and non-space consuming.

Another object of the present invention is to provide an improved memory switching system for storing a plurality of mechanical positions of a plurality of movable members, such system employing fewer moving parts.

It is another object of the present invention to provide an improved memory switching system for storing a plurality of switching combinations of a plurality of manually movable switch members on a musical instrument or the like, wherein such mechanical switch members not only perform their usual function with respect to the musical instrument but also act as input means, output means, and temporary storage means for the memory system.

It is another object of the present invention to provide an improved memory switching system wherein a magnetic memory effectively directly controls the position of mechanical switching members.

It is another object of the present invention to provide an improved memory switching system of Simpler, more economical. and more compact construction.

The subject matter which I rega d as my invention is particula ly pointed out and distinctly claimed in the concluding portion of this specification. The invention, however, both as to organization and me hod of operation, together with further advantages and objects thereof, may best be understood by reference to the following descrip ion taken in connection with the accompanying drawings wherein like reference characters refer to like elements and in which:

FIG. 1 is a block diagram of a memory switching system in accordance with the present invention; and

FIG. 2 is a schematic diagram of such a system.

Referring to FIG. 1, a magnetic core memory plane 10 comprises an array of magnetic cores each having two stable states of magnetization. These cores are of the type generally employed in magnetic memories, exhibiting substantially rectangular hysteresis loop characteristics, and are suitably electrically arranged in bit columns and word rows. According to a principal application of the present invention, the word row locations each represent a separate setting for stoptablets or draw knobs for an organ or other musical instrument. The bit columns then represent individual stop tablets or knobs receiving different settings from the memory according to the word location selected.

A stop tablet is illustrated schematically at 12 in the drawing and in accordance with the present invention includes a magnetically operated mechanical switching device having actuating means in the form of Coils 14 and 16, and position detecting means comprising grounded movable contact 22 and fixed contacts 18 and 20. Coil 14, When energized, causes movable contact 22 to close against fixed contact 18. When coil 16 is energized, movable contact 22 is caused to close against fixed contact 20. Both of these conditions are stable conditions, that is, when movable contact 22 is caused to move to either of the fixed contacts, such a condition is maintained until changed by appropriate energization of an operating coil or changed manually. The thus far described portion of the stop tablet is only the control portion. It is to be understood that the tablet further comprises a manually operable lever or the like circuitry or mechanism controlled thereby for appropriately altering the tonal qualities of the musical instrument.

The fixed contacts 18 and 20 are coupled to a pair of bit columns of magnetic cores in the magnetic core memory plane and are used for writing information into the memory plane indicative of the physical position of a stop tablet. This writing is accomplished in conjunction with the operation of bit write amplifier 24, also coupled to the same cores in the memory plane.

The stop tablet not only comprises the input means for the memory plane but also comprises the output means therefor. Thus information initially inserted into the memory plane by means of the setting of the stop tablet, is also read out as a physical setting of the same stop tablet. For this purpose means 26, comprising a bit sense and SCR circuit, is inserted bet-ween the memory plane and the stop tablet 12. Means 26 operates coils 14 and 16 of the switching device, the input for means 26 coming from the same bit column of cores to which the same switching devices fixed contacts 18 and were coupled. Thus, information may be read into the memory plane, for example, by means of a manual setting of the stop tablet, and then the same information may subsequently be read out via the bit sense circuits and SCRs, causing the stop tablet to resume such preset physical position.

A number of stop tablet settings, termed combinations, may be stored in the memory plane at separate word row locations thereof. When information is to be entered into the memory plane from a particular stop tablet, word write driver 28 is activated for a desired row wherein the information is to be entered. Operation of word write driver 28 is coordinated with bit write amplifier 24 for writing the information. Then, when information for a particular combination stored is to be read out, word read driver 30 is energized for this particular row and the information passes to the stop tablet via bit sense circuits and SCRs 26.

Although the explanation given thus far has made particular reference to tablet 12, it is to be understood that such a stop tablet including its switching means exists for each pair of bit columns in the magnetic core memory plane. Thus all the stop tablets on an instru ment may be automatically positioned in any one of a number of desired preset combinations. In an electronic organ or pipe organ there may be one set of general combinations for the stop tablets and sets of combinations for e ch di i ion of the g h gr a e l n choir divisions. Each such combination is stored in a word row of the memory plane.

Referring again to FIG. 1, a particular combination switch piston 32 is employed to select a particular combination which is to be read out as the physical position of the stop tablets. Of course, a combination switch piston is provided for each memory location storing a combination. A read and write monostable rnultivibrator 34 corresponding to each such combination switch piston 32 provides a pulse 36 when combination switch piston 32 is actuated. This pulse is differentiated to produce a spike 38 at the beginning of pulse 36, and a spike 40 at the end of such pulse. Spike 38 is applied to Word read driver 30, and spike 40 is applied to Word write driver 28. When the combination switch piston is depressed, word read driver 30 causes information to be read out via bit sense circuits and SCRs 26 for changing the position of each stop tablet through operation of coils 14 and 16. As 'will be appreciated by those skilled in the art, read out will be destructive in the usual form of magnetic core memory, so that once a particular word corresponding to a particular combination switch piston is read out as a physical position of the stop tablets, the corresponding word row in the memory plane no longer contains the information. However, spike 40 next energizes word write driver 28 and bit write amplifier 24 such that the same information is read back into the memory plane at the same row, inasmuch as fixed contacts 18 and 20 provide a position detecting function for reading the stop tablets physical position back into the selected memory row.

As indicated by its name, bit sense circuits and SCRs 26 include silicon controlled rectifiers operated by memory plane 10 and which function to operate coils 14 and 16. When the silicon controlled rectifiers have been rendered conducting, control is lost thereover, and therefore disconnect monostable multivibrator 42 is employed for operating SCR disconnect and set circuit 44 at a time substantially concurrent with writing of new information into a word row by means of bit write amplifier 24 and word write driver 28.

When it is desired to set a newcombination of stop tablets into the memory, set switch piston 48 is depressed after the stop tablets are physically set to the desired combination, and then a selected combination switch piston 32 is depressed. Set switch piston 48 operates SCR disconnect and set circuit 44 such that bit sense circuits and SCRs 26 cannot operate coils 14 and 16 of the stop tablet. Thus, spike 38 from read and write monostable multivibrator 34 has no effect, but information is only read into the selected word row of the memory plane, this information corresponding to the desired combination physically set upon the stop tablets.

A cancel switch piston 50 is provided for returning all stop tablets to the off position without altering information stored in the memory. The cancel switch piston 50 operates cancel monostable multivibrator 52 and the bit sense circuits and SCRs 26 corresponding to all of the stop tablets, causing all of the stop tablets to return to their off position. At the conclusion of this operation, cancel monostable multivibrator 52 operates disconnect monostable multivibrator 42, returning the silicon controlled rectifiers to their nonconducting state. SCR disconnect and set circuit 44, in addition to operating bit sense circuits and SCRs 26, also disconnects combination switch piston 32 and cancel switch piston 50 when the silicon controlled rectifiers are disconnected. This prevents information from being read from the memory and being destroyed when the silicon controlled rectifiers are momentarily in no position to receive and read out this information. Also cancel information is not applied to the silicon controlled rectifiers when they are thus disabled.

The FIG. 2 schematic diagram is exemplary of specific circuitry employed in an embodiment of the present in-. vention, his circ try or e pond ng function lly to the block diagram of FIG. 1. Read and write monostable multivibrator 34 includes cross-coupled transistors 54 and 56, transistor 54 normally being in a conducting state. The collectors of these transistors drive emitter follower transistors 58 and 60, by way of differentiating circuits 62 and 64. A triggering circuit, including the series combination of resistor 68, capacitor 70 and resistor 72, is disposed between volts and ground. The normally open contacts of combination switch piston 32 connect the junction between resistor 68 and capacitor 70 to ground through contacts of the relay 74 which contacts are ordinarily closed. The junction between resistor 68 and capacitor 70 is also coupled by way of triggering capacitor 76 to a voltage divider comprising resistors 78 and 80 disposed between the base of transistor 54 and the collector of transistor 56. During the quiescent condition, capacitor 70 charges up to approximately l0 volts, as does capacitor 76. When combination switch piston 32 is depressed, capacitor 76 discharges into the base of transistor 54 cutting off this transistor. At this time transistor 56 conducts for approximately 100 milliseconds. At the beginning of this unstable period, a positive going pulse 38 is supplied to the base of transistor 82 of the word read driver 30, by way of emitter follower transistor 60. The collector of transistor 82 is coupled for providing current fiow through a word row of magnetic cores in memory plane 10 by way of resistor 84, with resistor 84 limiting this current to a predetermined value. The value is sufficient to drive all the cores to a first or zero state by current flowing through the cores in the direction indicated in the drawing. Those cores previously in the one state will provide an output on sense conductor 86 or 90, thus supplying an input for transistor 92 or transistor 94.

Although sense conductors 86 and 90 are illustrated as passing only once through the cores of a given bit column, it is actually preferred to pass the sense conductors a plurality of times through the cores of a column. In a specific embodiment, six turns were employed for providing a total output of about 360 millivolts at a time when a stored one is sensed. This amplitude is desired for overcoming the forward Zener characteristic of transistors 92 and 94 and for causing them to conduct heavily enough for their respective collectors to bottom.

Means 26 also includes silicon controlled rectifiers 100 and 102. A voltage divider comprising resistors 104, 106 is connected between the cathode of silicon controlled rectifier 100 and the collector of transistor 92 and comprises the load resistance for the latter. The gate or control element of silicon controlled rectifier 100 is connected to the midpoint between resistors 104 and 106. Resistor 106 between the cathode and the gate of silicon controlled rectifier 100 is selected to enable the silicon controlled rectifier to block its rated voltage over its rated operating temperature range. Also, the voltage divider 104, 106 prevents the gate to cathode voltage from exceeding rated voltage. Transistor 92 provides as much voltage as possible within the rated range in order to be certain that the silicon controlled rectifier 100 will fire On a sensed pulse of short duration, e.g. about 2 microseconds. The transistor 92 amplifier stage is not necessary when silicon controlled rectifiers are employed capable of rapid turn On at low input voltage. In such case the sense conductors usually employ a greater number of turns for operating the silicon controlled rectifiers.

Silicon controlled rectifier 100 drives operating coil 16 of the stop tablet 12. Because of the inductive nature of this load and the short duration of the driving pulse, resistor 108 is employed in parallel with operating coil 16, this resistor allowing the current to build up to a holding value in the silicon controlled rectifier. Then the silicon controlled rectifier remains on after the input from the memory plane is removed, with the silicon controlled rectifier continuing to apply power to operating coil 16, causing the stop tablet to move in a direction such that movable contact 22 engages fixed contact 20. Of course, the operating lever is also moved as well as other mechanism or circuitry (not shown) connected with the musical instrument. About seventy milliseconds are required for the stop tablet to be moved from one position to the other by means of the operating coil. The silicon controlled rectifier is then disconnected from its power source in a manner hereinafter described.

Transistor 94 is also provided with a collector load resistance 110, 112. Again, a resistor 112 between the cathode and gate of silicon controlled rectifier 102 is selected for enabling silicon controlled rectifier 102 to block its rated voltage over its rated operating temperature range. Also, resistors 110 and 112 provide a voltage divider to prevent the gate to cathode voltage of silicon controlled rectifier 102 from exceeding its rated voltage. At the same time this voltage is arranged to be sutficient, when input is received from the memory plane, in order to be certain that the silicon controlled rectifier will fire on a short duration pulse, e.g. of about two microseconds in length. The silicon controlled rectifier 102 drives operating coil 14 in parallel with resistor 114 in the same manner as hereinbefore described in connection with silicon controlled rectifier 100.

A voltage divider, comprising resistors 116 and 118 disposed between a :12 volts and ground, applies a reverse bias to transistors 92 and 94 so the transistors will not be incorrectly operated and will therefore not provide an output corresponding to a disturbed zero read from a core in the memory plane. That is, a core exhibiting zero direction of retained magnetization, but one which has been partially demagnetized, will not provide a false indication when driven in the zero direction, provided transistors 92 and 94 are properly biased. Resistor 116 is a thermistor and therefore helps compensate for the thermal effect on the core output and the thermal effect of the forward Zener characteristic of the transistor. The output of the cores tends to increase with increase in temperature while the Zener voltage decreases. Since the thermistors resistance decreases with increase in temperature, the cumulative effect of core output and transistor Zener characteristic is counter-balanced.

Thus far, the stop tablet 12 has been described as being moved to a position corresponding to information stored in a particular row of the memory, e.g. row 96. In each row, a pair of cores, e.g., cores 120 and 122, are used to store a given position for a stop tablet. Assume core 120 of word row 96 stores a one in the form of a counterclockwise direction of retained magnetization, and assume core 122 stores a zero as a clockwise direction of retained magnetization, Then the read spike 38 applied to transistor 82 of word read driver 30 will drive core 120 from a stored one condition to a stored zero condition and the resulting output on the sense conductor 86 will cause heavy conduction in transistor 92. Transistor 92 will drive silicon controlled rectifier 100 into conduction thereby energizing operating coil 16 and moving the stop tablet to a desired position, as indicated on the drawing. At this time, since core 122 is already set in the zero direction of magnetization, substantially no output is produced therefrom. When core 120 stores a one and core 122 stores a zero, one particular position of the stop tablet is stored, On the other hand, if core 122 had stored a one and core 120 had stored a zero, the opposite position of the stop tablet would have been stored, and could have been read out to physically move the stop tablet into such position.

After reading the magnetic memory to physically position a stop tablet, such position is read back into the same memory cores. Read and write monostable multivibrator 34 remains in its unstable condition for approximately 100 milliseconds after combination switch poston 32 is depressed. At the conclusion of this time, positive spike 40 is produced at the emitter of transistor 53. This spike 40 is applied to word write driver 28 comprising transistor 124, transistor 124 providing current in an upward direction through cores 120 and 122 and resistor 126. This current is arranged to be approximately one-half the necessary drive for causing the cores in row 96 to switch to the one state. However, for every pair of cores corresponding to a stop tablet, only one will be driven to the one state depending upon the physical position of the corresponding stop tablet. The other half drive necessary to accomplish magnetization of a core back to the one state is derived from bit write amplifier 24.

Bit write amplifier 24, comprising cascaded transistors 128 and 139, receives its input from word write driver 28 via diode 133 and provides a current in column drive conductor 132 or column drive conductor 134 from ground towards transistor 130 depending on the position of movable switch contact 22 of the stop tablet. Such current, passing either through resistor 136 or resistor 138, has a value sup lying the remaining one-half of the necessary drive for causing a core to switch to the one state. Assuming the movable contact 22 of stop tablet 12 is in the position shown, making connection with fixed contact 20, then core 120 will be driven to the one state while core 122 remains in zero state. It is noted this is the original state of magnetization for the two cores, Thus far, the information regarding positioning of stop tablet 12 has been read from the memory to physically position stop tablet l2, and then the same information has been written back into the memory so the information is not lost. Resistor 140 from diode 133 to ground provides loading on the word write drive conductors so that the voltage induced on them during the read pulse period will not cause a column write current.

One read and write monostable multivibrator 34 and piston 32 is employed for each combination for which storage is desired in the instrument. Also, of course, a separate word write driver, 28, is provided for each combination or word in the memory. The various word write drivers are connected to bit write amplifier 24 through a plurality of diodes 133. Such other word write drivers drive other word rows in the memory, for example a row 98.

It is also understood that further stop tablets including further electromagnetically operable mechanical switching devices and associated circuitry are associated with further columns of cores in the memory plane. Thus, for each stop tablet and each combination setting, two magnetic cores are involved. The total number of magnetic cores equals the number of stop tablets multiplied by the number of combination settings multiplied by two. One bit write amplifier 24 may be employed for each pair of bit columns associated with one stop tablet, or a larger bit writ amplifier supplying sulficient drive current may be employed for all bit columns.

The bit write output pulse from bit write amplifier 24 is sampled through diode 142 and used to trigger disconnect monostable multivibrator 42. Disconnect monostable multivibrator 42 includes a first transistor 144 and a second transistor 146 cross-coupled so that transistor 144 is normally conducting in the multivibrators stable state. Negatively poled diode 142 is coupled to the base of transistor 146 through the series combination of resistor 148 and diode 150. A speedup capacitor 152 shunts resistor 148, while positive diode 154 shunts the base of transistor 146 to ground. Monostable multivibrator 42 is therefore responsive to negative drive pulses from bit write amplifier 24. The negative pulse from bit write amplifier 24 causes transistor 146 to conduct and transistor 144 to become nonconducting for producing a positive-going pulse at the collector of transistor 146. This pulse is supplied to transistor 156 driving transistor 158 in cascade. Transistor 158 drives emitter-follower transistor 160 having its emitter coupled to the cathodes of silicon controlled rectifiers 100 and 102. When the negative pulse is received from bit write amplifier 24, the disconnect monostable multivibrator 42 is switched to its unstable state wherein transistor 146 conducts. The positive-going pulse on the collector of transistor 146 cuts off transistor 156 and transistors 158 and are also thereby cut off whereby silicon controlled rectifiers 100 and 102 are disabled. Thus the silicon controlled rectifiers are temporarily disconnected such that their gate elements can regain control thereover for subsequent readout of information to the stop tablet.

Set switch piston 48 is also connected to SCR disconnect and set circuit 44. The set switch piston, when operated, discharges capacitor 162 in parallel with resistor 164 connected from the base of transistor 156 to ground. Closing of set switch piston 48 then removes the usual negative voltage from the base of transistor 156 whereby this transistor ceases to conduct and power is removed from the silicon controlled rectifiers in substantially the same manner as set out above. If set piston 48 is depressed after the stop tablets have been manually placed in a desired position, and then the combination piston is depressed, no information will be read out to the stop tablets, that is their manually set positions will be retained, and the physically accomplished setting thereof will be read into the selected combination word location of the memory plane. Capacitor 162 slows the rise time of voltage across the base of transistor 156 when the set piston is released so the silicon controlled rectifiers do not spontaneously trigger.

Transistor 168 is also driven from the collector of transistor 146 and operates relay 74. Transistor 168 normally conducts and the contacts of relay 74 normally operate for grounding one side of pistons 32 and 50, that is when disconnect monostable multivibrator 42 is in its quiescent condition. However, when multivibrator 42 is in its unstable state, transistor 168 allows the relay to drop out disconnecting the aforementioned pistons. Therefore, information cannot be read out from the memory when the silicon controlled rectifiers are disabled, nor can the Setting of stop tablets be canceled at this time.

The purpose of the cancel monostable multivibrator 52 is for returning of all stop stablets to a uniform of off position. The multivibrator 52 is substantially similar to multivibrator 34 in its operation and includes first and second crossvcoupled multivibrator transistors 170 and 172, and output transistors 174 and 176 coupled to the aforementioned multivibrator transistors by means of differentiating circuits 178 and 179. A triggering circuit 182 couples cancel piston 50 to the multivibrator. When the cancel switch piston is depressed, normally conducting transistor 170 ceases to conduct and transistor 172 conducts. A positive-going spike is applied to transistor 176 which drives transistor 177 to apply a positive-going pulse through diode to the collector of transistor 92. The positive pulse applied at this point energizes the bit sense circuits and SCRs to place the stop tablet in its off position. The collector of transistor 177 is coupled to the means 26 associated with each stop tablet. At the conclusion of the unstable period for multivibrator 52, a negative-going pulse is applied to the base of transistor 146 of multivibrator 42 through resistor 183 and diode 184.

According to the present invention, the stop tablets and/or knobs of an organ or other musical instrument may be manually set, or the stop tablets may be set from selected combinations stored in the magnetic memory. When a selected combination piston is depressed, all the stop tablets are moved electromagnetically to their positions as dictated by such stored combination. And, of course, a different combination of settings may be placed upon the stop tablets at any time by merely depressing a different combination piston corresponding to the different desired stored settings. All stop tablets may be at any time returned to the same off position by depressing the cancel piston. In order to store a new setting of stop tablets at a combination location in the memory, it is merely necessary to manually set the stop tablets in the desired combination, depress the set piston, and depress the combination piston. This combination piston will then represent to the operator the combination setting thus stored. The system according to the present invention is capable of providing storage for a large number of combinations of the stop tablets of an instrument. At the same time, storage of such number of combinations is relatively inexpensive and compact; not requiring extensive physical space in the instrument. The system is applicable not only to electronic organs but also to pipe organs and other systems and instruments employing selectable settings of a number of operating elements for operation thereof.

The present system provides for both manual operation of the stop tablets and for electrical operation thereof from storage. The combination of stop tablets with magnetic storage provides system simplification and advantageous cooperation between stop tablets and storage. Not only does the magnetic memory store the position of the stop tablets, but the stop tablets achieve a physical position under the control of the magnetic memory which is then used in an input for placing the same information immediately back into the magnetic memory whereby a particular combination setting is not lost in readout. Moreover, of course, the stop tablets provide a manually settable input to the magnetic memory. Thus, the stop tablets, when employed in conjunction with a magnetic memory, comprise the magnetic memorys input means, its output means, and temporary storage means for immediate return of information to the memory after readout. The stop tablets also, of course, accomplish their intended function with respect to the organ or other instrument.

While I have shown and described a preferred embodiment of my invention, it will be apparent to those skilled in the art that many changes and modifications may be made without departing from my invention in its broader aspects. I therefore intend the appended claims to cover all such changes and modifications as fall within the true spirit and scope of my invention.

I claim:

1. A memory switching system comprising:

a plurality of physically movable members having at least two selectable positions and having electrical actuating means and position detecting means,

a magnetic memory comprising an array of magnetic elements for storing at separate locations a plurality of separate combinations of positions of said movable members, each of said elements exhibiting substantially rectangular hysteresis loop characteristics, the movable members comprising both input and output means for said array,

first electric circuit means for selectively coupling the position detecting means of said movable members to said array of magnetic elements for determining the retained magnetization of selected elements and storing at selected locations of said array a memory pattern corresponding to the position of said movable members at a given time, and

further selectively operable circuit means for coupling said array of magnetic elements to the actuating means of said movable members for establishing the physical position of said movable members in accordance with the said memory pattern at selected locations.

2. The system according to claim 1 wherein said movable members act temporarily to store by their physical position the said memory pattern for substantially immediate reintroduction thereof into said memory array by said first electrical circuit means.

3. The system according to claim 1 wherein said movable members are adapted to be manually controlled.

4. The system according to claim 1 wherein said movable members comprise electromagnetically operable relay switch members including actuating coils comprising the said electrical actuating means and relay contacts comprising the same position detecting means.

5. The system according to claim 1 wherein said array includes a word group of magnetic cores comprising each said location with at least one core representing each movable member at such location.

6. The system according to claim 5 including a pair of cores corresponding to each movable member at each location wherein magnetization of one of said pair of cores in a given direction corresponds to one selectable position for said movable member and magnetization of the other of said two cores in a given direction corresponds to a second selectable position for said movable member.

7. The system according to claim 1 further including electrical control means for causing said further selectively operable circuit means to couple a given location of said array of said magnetic elements to the actuating means of said movable members followed by immediate operation of said first electrical circuit means for immediately coupling the position detecting means of the said movable members to the said location for restoring the information at said location in said array.

8. The system according to claim 7 wherein said electrical control means includes a pulse generator coupled to the magnetic elements of one location for pulsing all such elements at such location in a first polarity direction to cause operation of said further selectively operable circuit means, followed by operation of said first electrical circuit means including pulsing of the magnetic elements of said one location in an opposite polarity direction to rewrite the positions of said movable members at said location in said memory array.

9. The system according to claim 1 wherein said further selectively operable circuit means couples the magnetic elements corresponding to a given movable member at several different memory locations to the actuating means of said movable member, said circuit means including a silicon controlled rectifier receiving a controlling input from said memory array and connected for operating the actuating means of said movable member.

10. The system according to claim 9 including drive amplifier means coupled to said memory array by said position detecting means.

11. The system according to claim 9 including circuit means for deenergizing said silicon controlled rectifier when information is coupled to said array from the position detecting means of said movable members by said first electrical circuit means.

12. The system according to claim 8 including one such pulse generator means for each location of said memory array, and a combination piston for operating each said pulse generator means.

13. The system according to claim 1 including cancelling circuit means for returning all said movable members to a given position.

14. A memory switching system comprising:

a plurality of stop switch members adapted to be manually controlled from an organ console having electrical actuating coils associated with each such stop switch member for positioning such switch member in at least two selectable positions, and position detecting contacts associated with each such stop switch member,

a magnetic memory comprising an array of magnetic cores for storing at separate word locations a plurality of separate combinations of said stop switch members, each of said cores exhibiting substantially rectangular hysteresis loop characteristics, the same stop switch members comprising both input and output means for said magnetic memory,

first electrical circuit means for selectively coupling the position detecting contacts of said stop switch members to corresponding bit position cores in a plurality of said locations for determining the retained magnetization of such cores at manually selected locations causing such cores at such locations to retain magnetization corresponding to the physical position of the stop switch members at that time, and

further selectively operable circuit means for coupling the cores corresponding to stop switch members to the actuating coils of such stop switch members for establishing the physical position of the stop switch members in accordance with the memory pattern at manually selected locations, said further selectively operable circuit means including silicon controlled rectifiers under the control of said magnetic cores for operating said actuating coils,

pulse generator means for selecting a given location in said memory, and

a combination piston connected to said pulse generator for manual selection of each such manually selected location.

15. The system according to claim 14 wherein said stop switch members act temporarily to store by their physical position the said combinations for substantially immediate reintroduction thereof into said memory array by said first electrical circuit means.

16. The system according to claim 14 wherein said pulse generator means causes said further selectively operable circuit means to couple a given location of said array of magnetic cores to the actuating coils of said stop switch members followed by immediate operation of said first electrical circuit means for immediately coupling the position detecting contacts of said stop switch members to the said location for restoring the information at said location in said array.

17. A memory switching system comprising:

a plurality of stop switch members adapted to be manually controlled from an organ console having electrical actuating coils associated with each such stop switch member for positioning such switch member in at least two selectable positions, and position detecting contacts associated with each such stop switch member,

a magnetic memory comprising an array of magnetic cores for storing at separate word locations a plurality of separate combination of said stop switch members, each of said cores exhibiting substantially rectangular hysteresis loop characteristics, the same stop switch members comprising both input and output means for said magnetic memory,

first electrical circuit means for selectively coupling the position detecting contacts of said stop switch members to corresponding bit position cores in a plurality of said locations for determining the retained magnetization of such cores at manually selected locations causing such cores at such locations to retain magnetization corresponding to the physical position of the stop switch members at that time,

further selectively operable circuit means for coupling the cores corresponding to stop switch members to the actuating coils of such stop switch members for establishing the physical position of the stop switch members in accordance with the memory pattern at manually selected locations, and

means for normally operating said further selectively operable circuit means followed by substantially immediate operation of said first electrical circuit means for temporarily storing the memory information at a given location by the physical position of said stop switch members with immediate reentry of said information into said memory location from said stop switch members.

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3,192,512 6/ 1965 Korkowski.

3,307,050 2/1967 Castle 307- 112 3,372,385 3/1968 Kikuchi.

3,412,197 11/1968 Weitzner 84-103 ROBERT s. MACON, Primary Examiner T. B. JOIKE, Assistant Examiner US. Cl. X.R. 340-147, 166

igigi UNITED STATES PATENT QFFICE CERTIFICATE OF CORRECTION Patent No. ,497,714 Dated February 24, 1970 Invencorbs) Patrick M. Castle I It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, line 53, "furture" should be future Column 3, line 27, after "like" should be inserted and Column 6, line 26, '1 '12" should be +12 Column 6, lines 72, 73, "poston" should be piston Column 8, line 40, "stablets" should be tablets Column 8, line 40, "of", second occurrence, should-be or Column 9, line 51, "electric" should be electrical Column 9, line-75, "same" should be said combinations SIGNED AND SEALED- AUG 4 -1979 EdwardlLFIemhenIr. Atteating Officer WILLIAM E; BGHUYIm, JR. Commissioner of Patents 

